Altitude-instrument



. B. B. SHARP.

ALTITUDE INSTRUMENT.

(N0 Moqel.)

No sss ss. Patented Jan. 5, 1886'.

rwenboT-a alt "n" u UNITED STATES PATENT OFFICE.

BENJAMIN BARTON SHARP, OF SAN FRANCISCO, CALIFORNIA.

ALTITUDE-INSTRUMENT.

EPEGIFICATION forming part. ofLetters Patent No. 333,555, dated January 5, 1886.

Application filed March 31, 1385.

To all whom it may concern.-

Be it known that I, BENJAMIN BARTON SHARP, a resident of San Francisco, State of California, have invented a novel and useful Anglemeter; and I hereby declare that the following is a full, clear, and exact description of the same, reference beinghad to the accompanying drawings.

My invention relates to a novel means for measuring altitudes and ascertaining time during day or night.

The following description fully explains the nature of my said invention, and the manner in which I proceed to construct, apply, and use the same, the accompanying drawings being referred to by figures and letters.

Figure 1 represents the stern of a vessel, showing the position of the anglemeter. Fig. 2 is an enlarged view of the anglemeter mounted. Fig. 3 is a plan view of the anglemeter. Fig. 4: represents elevation of the cross-bar, showing spirit-levels. Fig. 5 is a plan view of the same. Fig. 6 is an enlarged view of the anglemeter, showing indeX-bar and nonins or Vernier. Fig. 7 is an end view of the telescope, sh owing eyepiece and shade.

The stern of a boat is represented in Fig. 1 by the letter a. Upon this is shown the stand and anglemeter at I).

My device, which I call an anglemeter, 1), consists of a graduated arc, b*, of ninety degrees, having an indexbar, l, and nonins or Vernier n, tangent-screws 0 and clamp, and a telescope, an, attached to the face of the indexbar, and having an eye-piece, q, and shade r, and a cross-wire at its farthest extremity. The telescope is held to the index-bar by bands m having set-screws p by means of which the telescope may be revolved and held in place. The anglemeter is mounted upon a movable hollow frame or stand, 0, of conical or pyramidal form, and of a suitable height and diameter. In the center of this frame a pendulum, d, swings out and in the openings 6 on both sides of the lower part of the frame. The pendulum is attached to a cross-bar, it, through which a shaft, h, extends. On each of the cross-bars there is a lug, k, the horizontal flange of which is screwed to the cross-bar, and the vertical flange is perforated for the adj usting-screws 12*, attached to the anglemeter and acting in the slots 1). The face of the crossbar is rabbeted, j, for a slide and rest for the anglemeter on the upper surface of the cross-bar, and onits end there are spirit-levels i. A metallic ring, f, plays and rotates in a groove in the upper part of the frame, and within this ring there is another, 9, pivoted tof, and is adjusted as to using and 0scillates like a mariners compass on itsgimbals. The inner ring, 9, is notched for the gimbals of the shaft h to act, and it is adjusted to a horizontal position by the pendulum and its plane determined by the spirit-levels, Fig. 3.

This novel instrument combines perfect means for measuring altitudes. The entire field may be obscured, as the slots in both arms of the anglemeter, provided with adjusting-screws, permit the instrument to be attached by either of its radial limbs, and to allow a slight movement on the adjustingscrews by means of the slotsp in said limbs.

The adjustments of the instrument are so nice and accurate that after making an observation it is impossible to place the angles out of order.

After use, the anglemeter is removed to the cabin, where it is read and the result of the observation obtained, and the instrument is secured until it is again wanted. The frame may be removed or remain on deck under cover.

The anglemeter is an angle of ninety degrees, which describes that are of the heavens representing the horizontal limb, and of course the perpendicular limb-that is to say, the zenith. The vision is directed from right augle toward any part of the arc of ninety degrees, as seen direct from that angle, and the true altitude is at once obtained, less the sum of atmospheric refraction. There is no dip of the horizon,whatsoever the elevation of the eye above the surface. The center of the object is taken as readily as either limb, and consequently there is no semi-diameter. The apparent difference of position of the object or its parallax is of small moment, as amounts to only a few seconds in the case of a large altitude.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In an anglemeter, the combination of the frame or stand having the rings f and g, movable as described, across-bani, swungin ringg I k on top and the pendulum beneath, of the by means of a shaft. h, a pendulum attached graduated arc having the two radial limbs at to said cross-bar below and a graduated are, ninety degrees from each other, provided with 15 and radial limbs having a nonins or Vernier, slots 19, adjusting-screws for connecting the 5 n, indexbar Z, and telescope m, secured ad I radial limbs to lugs 75, and the Vernier n, barl,

justably to the upper side of the bar 75, as set and telescope, as described.

forth. In testimony whereof I have hereunto set 2. In an anglemeter, the combination, with my hand and seal. the stand having the rings f and g, as de- BENJAMIN BARTON SHARP. [n s.] 10 scribed, and the cross-bar t, having the shaft Vitnesses:

h, by means of which it is swung in the ringg, A. B. SMITH,

and provided with the spirit-levels i and lugs l J. HITOHIENS. 

